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Background Population/based studies about contact allergy are scarce. Objectives To obtain reliable estimates of the prevalence of contact allergy in the general population in Europe.Methods A cross-sectional study of a random sample from the general population, aged 18-74 years, in five different European countries (Sweden, the Netherlands, Germany, Italy and Portugal). In total, 12 377 subjects were interviewed and a random sample (n = 3119) patch tested to TRUE Test panels 1-3 and Fragrance Mix (FM) II, hydroxyisohexyl 3-cyclohexene carboxaldehyde (HICC) and sesquiterpene lactone mix. A positive patch test reaction is considered as contact allergy.Results In total, 27.0% [95% confidence interval (CI) 25.5-28.5] had at least one positive reaction to an allergen of the European baseline series, with a significantly higher prevalence in women than in men. The highest age-standardized prevalences (>= 1%) were found for nickel (14.5%, 95% CI 13.2-15.8), thiomersal (5.0%, 95% CI 4.2-5.8), cobalt (2.2%, 95% CI 1.7-2.7), FM II (1.9%, 95% CI 1.5-2.5), FM I (1.8%, 95% CI 1.4-2.3), HICC (1.4%, 95% CI 1.0-1.9), p-tert-butylphenol formaldehyde resin (1.3%, 95% CI 0.9-1.7) and para-phenylenediamine (1.0%, 95% CI 0.6-1.3). Only nickel and thiomersal showed a statistically significantly different prevalence for contact allergy among the different European populations. Subjects reporting contact dermatitis in their lifetime (age-standardized prevalence 15.1%, 95% CI 13.8-16.3) had an increased risk for contact allergy (odds ratio 1.9, 95% CI 1.5-2.5). The risk of having a contact allergy was not increased in those with atopic dermatitis (prevalence 7.6%, 95% CI 6.7-8.6; odds ratio 1.0, 95% CI 0.7-1.4).Conclusions Contact allergy to at least one allergen of the European baseline series was diagnosed in more than one-quarter of the general European population. Therefore measures to improve the primary prevention of contact allergy have to be enforced.

Background Contact allergy to fragrances is assessed mostly in clinical populations of patients. Studies in the general population are scarce and vary in their methodology across countries.Objectives To determine the prevalence of fragrance contact allergy in the European general population and to assess the clinical relevance of positive patch test reactions to different fragrances.Methods In five European countries (Germany, Italy, the Netherlands, Portugal and Sweden) a random sample from the general population aged 18-74 years was drawn. In total, 12 377 subjects were interviewed in this cross-sectional study and a random sample (n = 3119) was patch tested using the TRUE Test and Finn Chamber techniques. Patch test procedures were harmonized by mandatory training before the study and monitoring during the study.Results The highest prevalence for contact allergy of 2.6% [95% confidence interval (CI) 2.1-3.2] was found for fragrance mix (FM) I in petrolatum, with a high content of atranol and chloratranol, followed by 1.9% (95% CI 1.5-2.4) for FM II in petrolatum. The conservatively estimated prevalence of fragrance contact allergy was 1.9% (95% CI 1.5-2.5). This is defined as the existence of a positive patch test to FM I or FM II; any of their individual materials; Myroxylon pereirae; sesquiterpene lactones or 3- and 4-hydroxyisohexyl 3-cyclohexene carboxaldehyde that show clinical relevance, defined conservatively as lifetime avoidance of scented products and an itchy skin rash lasting > 3 days in a lifetime. Using the reported lifetime prevalence of any contact dermatitis instead of the lifetime prevalence of any itchy skin rash, the prevalence is 0.8% (95% CI 0.5-1.2). The prevalence rates of contact allergy to fragrances in women are about twice those in men.Conclusions This study helps to identify targets for prevention of fragrance allergy.